Mitsubishi Galant. Manual — part 249

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-221

CIRCUIT OPERATION

•

The injector power is supplied from the MFI relay
(terminal 1).

•

The PCM controls the injector by turning the
power transistor in the PCM "ON" and "OFF."

TECHNICAL DESCRIPTION

•

The amount of fuel injected by the injector is
controlled by the amount of continuity time the
coil is grounded by the PCM.

•

A surge voltage is generated when the injectors
are driven and the current flowing to the injector
coil is shut off.

•

The PCM checks this surge voltage.

DTC SET CONDITIONS

Check Area

•

Engine speed is lower than 1,000 r/min.

•

Throttle position sensor output voltage is lower
than 1.16 volts.

Judgment Criteria

•

Injector coil surge voltage (battery positive
voltage + 2 volts) has not been detected for two
seconds.

TROUBLESHOOTING HINTS (The most likely
causes for this code to be set are:)

•

Injector failed.

•

Open or shorted injector circuit, or loose
connector.

•

PCM failed.

DIAGNOSIS

Required Special Tools
MB991502: Scan Tool (MUT-II)

AK000618 AD

CONNECTORS:B-17,B-21,B-30

B-30

B-17

B-21

AK000555AB

CONNECTOR : A-21X

MFI RELAY

AK000280

CONNECTOR : C-39

PCM

AW

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-222

STEP 1. Using scan tool MB991502, check actuator test
item 02, 04, 06: Injectors.

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK"(OFF) position before
connecting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Start the engine and run at idle.
(3) Set scan tool MB991502 to the actuator testing mode for

item 02, 04, 06 Injectors.

(4) Warm up the engine to normal operating temperature: 80

°

C to 96

°

C (176

°

F to 205

°

F).

•

Does the idle state worsen when the injector is cut off.
(Does idling become unstable or does the engine stall)

(5) Turn the ignition switch to the "LOCK"(OFF) position.

Q: Is the actuator operating properly?

YES : It can be assumed that this malfunction is intermittent.

Refer to GROUP 00, How to Use Troubleshooting/
Inspection Service Points (

P.00-8

).

NO : Go to Step 2.

STEP 2. Check the connector at injector for damage.

a. Check the connector B-21 when checking No.2 cylinder.
b. Check the connector B-17 when checking No.4 cylinder.

c. Check the connector B-30 when checking No.6 cylinder.

Q: Is the connector in good condition?

YES : Go to Step 3.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection (

P.00E-2

). Then go to Step 10.

AC003081 AB

16 PIN

MB991502

AK000618 AD

CONNECTORS:B-17,B-21,B-30

B-30

B-17

B-21

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-223

STEP 3. Check the injector.
(1) Disconnect the injector connector B-21 <No.2 cylinder> or

B-17 <No.4 cylinder> or B-30 <No.6 cylinder>.

(2) Measure the resistance between injector side connector

terminal 1 and 2.

Standard value: 13

−−−−

16 ohm [at 20

°°°°

C (68

°°°°

F)]

Q: Is the resistance standard value?

YES : Go to Step 4.
NO : Replace the injector. Then go to Step 10.

STEP 4. Check the power supply voltage at injector
connector.
(1) Disconnect connector B-21 <No.2 cylinder> or B-17 <No.4

cylinder> or B-30 <No.6 cylinder> and measure at the
harness side.

(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal 1 and ground.

•

Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK"(OFF) position.

Q: Is the voltage normal?

YES : Go to Step 6.
NO : Go to Step 5.

AK000618 AD

CONNECTORS:B-17,B-21,B-30

B-30

B-17

B-21

AK000559

2

1

INJECTOR SIDE
CONNECTOR

AB

AK000560

1

2

B-17,B-21,B-30
HARNESS SIDE
CONNECTOR

AC

MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-224

STEP 5. Check connector A-21X at MFI relay for damage.
Q: Is the connector in good condition?

YES : Repair harness wire between MFI relay connector

and injector connector because of open circuit or
short circuit to ground.

a. Repair harness wire between MFI relay

connector A-21X terminal 1 and injector
connector B-21 terminal 1 when checking No.2
cylinder.

b. Repair harness wire between MFI relay

connector A-21X terminal 1 and injector
connector B-17 terminal 1 when checking No.4
cylinder.

c. Repair harness wire between MFI relay

connector A-21X terminal 1 and injector
connector B-30 terminal 1 when checking No.6
cylinder.

Then go to Step 10.

NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection (

P.00E-2

). Then go to Step 10.

STEP 6. Check for harness damage between MFI relay
connector and injector connector.

a. Check the harness wire between MFI relay connector A-

21X terminal 1 and injector connector B-21 terminal 1 when
checking No.2 cylinder.

b. Check the harness wire between MFI relay connector A-

21X terminal 1 and injector connector B-17 terminal 1 when
checking No.4 cylinder.

c. Check the harness wire between MFI relay connector A-

21X terminal 1 and injector connector B-30 terminal 1 when
checking No.6 cylinder.

Q: Is the harness wire in good condition?

YES : Go to Step 7.
NO : Repair it. Then go to Step 10.

AK000555AB

CONNECTOR : A-21X

MFI RELAY

AK000555AB

CONNECTOR : A-21X

MFI RELAY

AK000618 AD

CONNECTORS:B-17,B-21,B-30

B-30

B-17

B-21